The CAC Boomerang was a fighter aircraft designed and manufactured in Australia by the Commonwealth Aircraft Corporation between 1942 and 1945. Approved for production shortly following the Empire of Japan's entry into the Second World War, the Boomerang was rapidly designed as to meet the urgent demands for fighter aircraft to equip the Royal Australian Air Force (RAAF). The type holds the distinction of being the first combat aircraft to be both designed and constructed in Australia.[2]

Different variants of the Boomerang were manufactured under a series of corresponding production contract numbers CA-12, CA-13, CA-14 and CA-19, the aircraft supplied under each subsequent contract would incorporate various modifications, typically aimed at improving the aircraft's performance. The effectiveness of the Boomerang has been contested, the aircraft proving to be slower than contemporary fighter aircraft and thus rarely engaging in aerial combat. During early wartime operations, the Boomerang was mainly dispatched to equip home-based squadrons, freeing up other fighters for use elsewhere overseas. In later service, the Boomerang would commonly be used for ground support duties, cooperating with Allied army units, in addition to secondary roles such as aerial reconnaissance and air sea rescue.

Development

Background

During the mid 1930s, some political leaders observed that both the Empire of Japan and Nazi Germany had the appearance of having been making strides towards a heavy preparedness for war, which in turn led to several other countries commencing their own preparations in response.[3] However, in the case of Australia, the nation had no domestic aircraft industry, partially due to a historical preference for the procurement of both civil and military-orientated aircraft to be sourced overseas from manufacturers based in the United Kingdom, which had come about through strong political and cultural ties between the two nations. On 17 October 1936, with the encouragement of the Government of Australia, three companies came together to form a joint venture, registered as the Commonwealth Aircraft Corporation (CAC), which had the goal of assessing the viability of the development of a self-sufficient aircraft industry.[3]

Early on, CAC set about planning for the establishment of both engine and aircraft manufacturing and testing facilities at Fishermans Bend, Melbourne, Victoria, purchasing tooling and equipment from manufacturers in both Britain and the United States.[3] While the company initially pursued the development and production of the CAC Wirraway, a single-engine armed advanced trainer aircraft which was a licence-built version of the North American NA-16, the firm would promptly be presented with a strong demand for the provision of large quantities of military aircraft, in particular fighter aircraft, to equip the Royal Australian Air Force (RAAF).[3] In July 1940, at which point the United Kingdom was the sole European nation fighting against German in the Second World War, the Australian Government issued a statement advising that "from this date onward Australia can rely on England for no further supplies of any aircraft materials or equipment of any kind.[3]

While British manufacturers were the main source of RAAF aircraft, by 1942, the British aircraft industry had long been hard-pressed to meet the needs of the RAF for the ongoing War in Europe.[3] Although United States companies possessed enormous aircraft manufacturing capacity, their output was at this point destined for the air units of the United States Army Air Forces (USAAF), which were themselves engaged in the conflict. Even where capacity was found for new aircraft to be built overseas, their delivery would involve them being shipped over long distances in wartime conditions, with consequent delays and risking considerable losses, in particularly due to the German U-boat threat.[3] While USAAF fighters – such as the Curtiss P-40 Kittyhawk and Bell P-39 Airacobra – that were damaged during service in Australia could be rebuilt by Australian workshops and loaned to RAAF units, they were not available in sufficient numbers either.

Origins

In late 1941, Lawrence Wackett, Manager and Chief Designer of CAC, began examining the possibility of designing and building a new domestically-designed fighter aircraft.[3] The main challenge to this ambition was the fact that fighter aircraft had never been manufactured before in Australia; according to aviation author Rene J. Francillon, many experts considered that the licensed manufacture of a complete fighter aircraft would be beyond the capabilities of Australia's industry at that time.[3] Wackett quickly made the decision to use elements of aircraft which were already being produced in Australia. Only two military aircraft were in production at the time: the CAC Wirraway, based on the North American NA-16, and the Bristol Beaufort bomber.[4]

Overseas, the NA-16 had already become the basis of the North American NA-50 fighter (also known as the P-64), which had been used by the Peruvian Air Force in the 1941 Ecuadorian–Peruvian War. Crucially, CAC's licence to manufacture the Wirraway already contained a clause allowing the design to be modified.[4] Accordingly, Wackett decided to use the airframe of the Wirraway as a starting point for the design of the new domestic fighter; this choice had the advantage of requiring little additional tooling; it also had the effect of reducing the timescales that would be involved in the design phase and to establish the manufacturing of the new aircraft.[5]

Although British designers had reworked the twin-engined Beaufort into a successful attack aircraft – the Beaufighter – this was not a suitable basis for the sought-after single-engine interceptor aircraft. However, Australian-made Beauforts used 1,200 horsepower (890 kW) Pratt & Whitney R-1830 Twin Wasp engines, which were made under license at the CAC plant in Lidcombe, Sydney.[5] Another factor in favour of the engine was that it was already in use to power the Grumman F4F Wildcat fighters of the United States Navy, which helped make the Twin Wasp a logical choice to power the domestic fighter design.[5]

In December 1941, the management of CAC issued its authorisation to proceed with the detailed design of the new fighter aircraft.[5] The aircraft, which had received the internal designation of CA-12, used the wing, tail assembly, undercarriage, and center section of the Wirraway in combination with a new forward fuselage, which housed the larger Twin Wasp engine. It had a new single seat cockpit complete with a sliding hood, and carried an armament of two 20 mm Hispano-Suiza HS.404cannons along with four .303 machine guns.[5]The proposal was presented to the Australian Government, which promptly gave its approval; the government viewed the CA-12 as an appropriate insurance against the delay or cancellation of its order for US-built P-40 fighters, as well as a desire to maintain work at CAC; the ready availability of usable Wirraway components for the CA-12, the latter of which would greatly speed up any manufacturing program, was also viewed favourably.[8]

Accordingly, on 18 February 1942, the Australian War Cabinet authorised an order for 105 CA-12 aircraft; shortly thereafter, the name Boomerang was selected for the aircraft.[5] The ordering of production aircraft had been made in advance of any prototype being produced or maiden flight performed, thus the Boomerang had been effectively ordered 'off the drawing board'.